This invention has relation to the positive lubrication of bearings in structures where the bearing supports a shaft adapted to be rotated at relatively high speeds while the bearing is supported in a housing which is adapted to turn at a relatively low speed. The structure of the invention will be particularly useful in connection with the positive lubrication of a bearing supporting a vibratory shaft for concentric rotation with respect to a road roller or drum forming part of a road, earth or other surface compacting machine, the bearing being supported to rotate with the drum.
It has been common practice to use a slinger ring attached around a rotating part to dip into an oil sump and to thereby spray oil off the periphery of the ring creating an oily atmosphere to lubricate the bearings. This method generates considerable heat which represents wasted energy, and the total flow of the lubricating oil is not directed to the bearings. Instead a small part of the flow is expected to find its way into the bearings. This is not real positive lubrication. Also, in the case of a vibratory road roller or earth compacting machine, the vibratory shaft is not always turning when the machine is moving, and so the bearings supporting the vibratory shaft would get no fresh supply of oil from slinger rings during that time.
Another method used is to grease the bearings. However, it is desirable to rotate the vibratory shaft at speeds up to 2300 revolutions per minute (rpm), but rotational speeds of over 1800 rpm's are not practical using grease, as the lubricative film afforded by the grease breaks down at higher speeds.
The need for effective lubrication can be lessened by increasing the diameter of the bearing to obtain more load bearing surface. To reach the speeds necessary for effective operation of the vibratory shaft, however, the additional forces involved due to the larger diameter of the moving parts are such as to tend to destroy the bearings.
In order to produce the desired vibratory effect, the vibratory shaft must carry an offset outwardly extending weight. The level of oil in any oil sump must be at all times below the vibratory shaft and its offset weight in order to prevent foaming of the oil with commensurate loss of lubricative qualifies, and in order to prevent heating of the oil with its commensurate wasted energy losses.
It is known, in connection with the lubrication of differential mechanisms such as are employed in vehicle final drives, to supply oil to the carrier of the differential mechanism near its axis of rotation so that the centrifugal forces may be utilized to urge the oil to flow radially outwardly through passages in the carrier, directing the oil to the carrier's internal components, in situations where the carrier is normally operated at relatively high rotative speeds. It is also known, where the carrier is to be normally operated at relatively low rotative speeds to provide scooops or cups around the carrier to lift the oil upward as the carrier rotates so that it may drain radially inward by gravity through passages of the carrier directing the flow to the carrier's internal components. Structures have also been devised to utilized the centrifugal forces when the carrier is operating at high rotative speeds and to use the gravitational forces when the same carrier is moving at low rotative speeds. See U.S. Pat. No. 3,741,343 granted to Lindenfeld et al in June of 1973.
This structure, however, does not suggest a means of providing positive lubrication to the bearings of a shaft moving at high rotative speeds concentric with another member moving at low rotative speeds and including the housing for said bearings.
The patent to Fekete et al, U.S. Pat. No. 1,787,428, granted in January of 1931, shows a structure in which gears affixed to a shaft in a gear casing dip into the oil or lubricant in the bottom of the casing thereby suitably lubricating the faces of the gears. The lubricant is thrown from the gears and splashed upon the walls of the casing, and runs down to a position where it is led onto the bearings. This method is not suitable for providing adequate and positive lubrication; and is somewhat similar to the system the present invention was designed to replace.
The patent to Williams, U.S. Pat. No. 3,301,349, granted in January of 1967, and the patent to Planch, U.S. Pat. No. 1,766,001, like the two patents listed above were located on a search of the prior art relative to the present invention. The Williams and Planch patents are also both related to splash type systems which the system of the present invention is designed to replace.
Applicant and those in privity with him know of no closer prior art than that set out above, and know of no prior art which anticipates the claims presented herewith.